JP2005298591A - Aqueous coating material composition and method of forming coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous coating material composition, which is excellent in low temperature curability that enables to obtain sufficient curability even in the baking condition of a relatively low temperature of 120°C or lower, adherability, one-package storage stability and resistance to yellowing by heat, and which is capable of attaining reduction of the volume of a solvent as a countermeasure for environmental problems, and to provide a method of forming a coating film. <P>SOLUTION: The aqueous coating material composition contains, as the essential components, an acrylic resin that contains, on an average per molecule, two or more of blocked tertiary isocyanate groups which are blocked by a nitrogen atom-containing heterocyclic compound and that has a specific acid number and weight average mol. wt., a hydroxy group-containing resin having a specific hydroxyl value and weight average mol. wt., and a catalyst. The method of forming a coating film is provided which uses the above. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an acrylic resin having a specific acid value and a weight average molecular weight, each containing at least two groups having blocked a tertiary isocyanate group in a nitrogen atom-containing heterocyclic compound, a specific hydroxyl value and a weight average. The present invention relates to an aqueous coating composition containing a hydroxyl group-containing resin having a molecular weight and a specific catalyst as essential components, and a coating film forming method using the same.

  A cured coating film obtained from a base resin such as an acrylic resin containing a functional group such as a hydroxyl group and a two-component or one-component paint containing a polyisocyanate-based crosslinking agent is excellent in chemical resistance, physical properties, weather resistance, and the like. It is widely used in the field of automotive paints.

  However, the two-component paint has drawbacks such as safety and hygiene problems due to the isocyanate cross-linking agent, limited pot life (pot life), and difficulty in washing the coating equipment due to thickening of the paint. Disadvantages such as high dissociation temperature of the blocking agent in the one-component paint with the isocyanate cross-linking agent as the block type, and a high baking temperature (usually 150 ° C or higher) are required to obtain sufficient coating performance. There is.

  As a method for solving these problems, for example, a self-crosslinkable resin having a hydroxyl group and an isocyanate group blocked with a blocking agent introduced in one molecule and a coating composition containing the same are disclosed (for example, Patent Documents). 1 or 2).

  However, in the above solution, the curing temperature is not sufficiently lowered, and at a baking temperature of 120 ° C. or less, the coating film is insufficiently cured. There was a problem that the coating film was colored by heating.

  In recent years, there has been an increasing demand for water-based coatings for the above-mentioned isocyanate-based crosslinking agent-curing coatings as a countermeasure against environmental problems.

Japanese Patent Laid-Open No. 10-316663

JP-A-5-247175

  The object of the present invention is to achieve sufficient curability even under relatively low-temperature baking conditions of 120 ° C. or lower, low-temperature curability, adhesion, one-part storage stability, and further, the coating film can be heated by baking. An object of the present invention is to provide a water-based coating composition and a method for forming a coating film that are not colored and can reduce the amount of solvent as a countermeasure for environmental problems.

  As a result of intensive studies to solve the above problems, the present inventors are particularly effective in applying a nitrogen atom-containing heterocyclic compound as a blocking agent for a tertiary isocyanate group, and a nitrogen atom-containing heterocyclic compound. An acrylic resin having a specific acid value and a weight average molecular weight, containing an average of two or more blocked tertiary isocyanate groups in a molecule, a hydroxyl group-containing resin having a specific hydroxyl value and a weight average molecular weight, and a catalyst are essential. It has been found that the above-mentioned problems can be solved by an aqueous paint composition characterized by containing it as a component and a coating film forming method using the same, and the present invention has been completed.

That is, the present invention provides: (A) An average of two or more blocked tertiary isocyanate groups blocked with a nitrogen atom-containing heterocyclic compound are contained in one molecule, the acid value is 3 to 100 mgKOH / g, and the weight average molecular weight is 1,000 to 100. Selected from acrylic resin, polyester resin, and urethane-modified polyester resin having a hydroxyl value of 10 to 250 mgKOH / g and a weight average molecular weight of 1,000 to 200,000. An aqueous coating composition comprising at least one hydroxyl group-containing resin and (C) a curing catalyst as essential components;
2. The blocked tertiary isocyanate group of the acrylic resin (A) is represented by the following formula (1) or (2)

Item 2. The water-based paint composition according to Item 1, wherein R ₁ and R ₂ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Stuff,
3. Item 3. The aqueous acrylic resin (A-1) obtained by neutralizing an acid group in the resin with a basic compound and dispersing in water as the acrylic resin (A). Water-based paint composition,
4). Particles obtained by emulsion polymerization of a radically polymerizable monomer containing a group represented by the formula (1) or (2), a carboxyl group-containing radically polymerizable monomer, and other radically polymerizable monomers as the acrylic resin (A) Item 3. An aqueous coating composition according to Item 2, wherein the aqueous acrylic resin (A-2) has a diameter in the range of 50 to 500 nm.
5). Item 5. The aqueous coating composition according to any one of Items 1 to 4, wherein the hydroxyl group-containing resin (B) has an acid value of 10 to 100 mgKOH / g.
6). Item 6. The aqueous coating composition according to any one of Items 1 to 5, further comprising polyolefin and / or chlorinated polyolefin,
7). The water-based coating composition according to any one of Items 1 to 6, further comprising a urethane emulsion,
8). Item 8. The aqueous coating composition according to any one of Items 1 to 7, further comprising a blocked polyisocyanate compound in which an isocyanate group is blocked with an amino resin and / or an active methylene group-containing compound,
9. Item 9. The aqueous coating composition according to any one of Items 1 to 8, further comprising an ultraviolet absorber and / or a light stabilizer.
10. Item 11. A multilayer coating film forming method for sequentially forming a primer layer, a colored topcoat basecoat layer, and a topcoat clearcoat layer on an object to be coated, wherein the coating composition that forms at least one of the layers is any one of Items 1 to 9 A method for forming a coating film, which is the water-based coating composition according to item 1,
11. Item 11. A multilayer coating film forming method for sequentially forming a colored topcoat basecoat layer and a topcoat clearcoat layer on an object to be coated, wherein the coating composition that forms at least one of the layers is any one of Items 1 to 9 A method for forming a coating film, characterized in that it is a water-based coating composition according to the description,
12 Item 10. The method for forming a coating film according to Item 10 or 11, wherein the article to be coated is a plastic material.
13. The vehicle body in which a coating film is formed by the coating film forming method according to Item 10 or 11,
It is related to.

  The aqueous coating composition of the present invention is excellent in one-component storage stability, can obtain sufficient curability and coating film performance even under relatively low-temperature baking conditions of 120 ° C. or lower, and further by heating during baking. The heat yellowing is good, and the effect of reducing the amount of solvent discharged for painting can be achieved.

Hereinafter, the water-based coating composition of the present invention will be specifically described.
The aqueous coating composition of the present invention comprises a nitrogen atom-containing heterocyclic compound block tertiary isocyanate group-containing acrylic resin (A), a hydroxyl group-containing resin (B) and a catalyst (C) as essential components.

Nitrogen atom-containing heterocyclic compound block tertiary isocyanate group-containing acrylic resin (A)
The component (A) of the coating composition of the present invention is an acrylic resin containing an average of two or more groups in which a tertiary isocyanate group is blocked with a nitrogen atom-containing heterocyclic compound in one molecule.

  Examples of the acrylic resin (A) include the following (A) and (B).

(A): A nitrogen atom-containing heterocyclic compound is reacted with a tertiary isocyanate group of a copolymer comprising a tertiary isocyanate group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer, and other radical polymerizable monomers. acrylic resin.
The copolymer can be synthesized by a known method according to a conventional method.
As the tertiary isocyanate group-containing radical polymerizable monomer, for example, the following formula (3)

The compound shown by can be mention | raise | lifted.
Specific examples of the compound represented by the general formula (3) include m-isopropenyl-α, α′-dimethylbenzyl isocyanate.

  Examples of the carboxyl group-containing radical polymerizable monomer include acrylic acid and methacrylic acid.

  Examples of other radical polymerizable monomers include styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and cyclohexyl (meth) acrylate. , Cyclohexenyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) ) Acrylate, Aronix M110 (manufactured by Toagosei Co., Ltd.), N-methylol (meth) acrylamide, N-butoxy (meth) acrylamide, acryloylmorpholine , Dimethylaminoethyl (meth) acrylate, N- vinyl-2-pyrrolidone, .gamma. (meth) acrylate, etc. b propyl trimethoxysilane can be exemplified.

  In the above, “(meth) acrylate” means “acrylate or methacrylate”.

  Examples of the nitrogen atom-containing heterocyclic compound to be reacted with a copolymer comprising a tertiary isocyanate group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer, and other radical polymerizable monomers include, for example, pyrazole, 3,5-dimethyl Examples include pyrazole compounds such as pyrazole such as pyrazole, 3-methylpyrazole and 3-methyl-5-phenylpyrazole, and pyrazole derivatives; and triazole compounds such as 1,2,4-triazole.

  Among those described above, 3,5-dimethylpyrazole or 1,2,4-triazole is used from the viewpoints of economy, curability when used as a curing agent, coating film performance of the obtained coating composition, and the like. Particularly preferred.

  In the above reaction, a nitrogen atom-containing heterocyclic compound is heated to a melting point or higher and melted into a copolymer composed of a tertiary isocyanate group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer, and other radical polymerizable monomers. Alternatively, the reaction can be carried out by adding a solution dissolved or dispersed in an inert solvent. The reaction temperature is preferably in the range of 60 to 140 ° C, particularly 80 to 120 ° C. The blending ratio of a nitrogen atom-containing heterocyclic compound to a copolymer comprising a tertiary isocyanate group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer, and other radical polymerizable monomers is theoretically determined as a nitrogen atom-containing complex. The equiequivalent ratio of the ring compound and the isocyanate functional group may be sufficient, but in order to facilitate the reaction, the nitrogen atom-containing heterocyclic compound is preferably used in an excess of 1 to 10% with respect to the amount of the isocyanate functional group. If it is used in excess, the unreacted nitrogen atom-containing heterocyclic compound will deteriorate the water resistance of the coating film. Conversely, if the amount is too small, it may take time to complete the reaction, or in some cases the reaction may be insufficient. There is.

  The inert solvent does not react with a copolymer comprising a tertiary isocyanate group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer, and other radical polymerizable monomers, and dissolves a nitrogen atom-containing heterocyclic compound. For example, toluene, xylene, ethyl acetate, n-butyl acetate, cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, methoxypropyl acetate and the like can be used. Further, some of these solvents may be mixed and used.

  (B): An acrylic resin obtained by copolymerizing a blocked tertiary isocyanate group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer and other radical polymerizable monomers blocked with a nitrogen atom-containing heterocyclic compound.

  The method for obtaining the blocked tertiary isocyanate group-containing radical polymerizable monomer is not particularly limited, and a known method can be used. For example, a tertiary isocyanate group-containing radical polymerizable monomer and a nitrogen atom-containing complex can be used. It can be produced by reacting a ring compound.

  Examples of the nitrogen atom-containing heterocyclic compound and the tertiary isocyanate group-containing radical polymerizable monomer include the same ones as described in (a) above.

  The above reaction is carried out by reacting a tertiary isocyanate group-containing radical polymerizable monomer with a nitrogen atom-containing heterocyclic compound heated to a melting point or higher, or by dissolving or dispersing it in an inert solvent. be able to. The reaction temperature is preferably in the range of 60 to 140 ° C, particularly 80 to 120 ° C. If the temperature is too low, the reaction will be too slow, and if it is too high, gelation may occur due to polymerization of C═C (double bond). The mixing ratio of the nitrogen atom-containing heterocyclic compound and the tertiary isocyanate group-containing radical polymerizable monomer may theoretically be an equivalent ratio of the nitrogen atom-containing heterocyclic compound and the isocyanate functional group, but the reaction is facilitated. Therefore, it is better to use the nitrogen atom-containing heterocyclic compound amount in excess of 1 to 10% with respect to the isocyanate functional group amount. If used in excess, the unreacted nitrogen atom-containing heterocyclic compound deteriorates the water resistance of the coating film. Conversely, if the amount is too small, it may take time to complete the reaction or may not be completed in some cases. Further, since there is an upper limit of the conversion rate depending on the reaction temperature, when the progress of the reaction stops, it is necessary to gradually lower the temperature to complete it.

  As the inert solvent, the same solvents as mentioned in the above (a) can be used in the same manner.

  In the above reaction, it is desirable to add a polymerization inhibitor in order to prevent polymerization. As the polymerization inhibitor, commonly used ones such as phenothiazine, p-methoxyphenol, 2,6-ditertiary butyl-4-methylphenol (BHT) can be used.

  Examples of the carboxyl group-containing radical polymerizable monomer and other radical polymerizable monomers include the same as those mentioned in the above (a).

  Further, a hydroxyl group-containing radical polymerizable monomer may be used in combination with the monomer. Examples of the hydroxyl group-containing radical polymerizable monomer include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, ε-caprolactone-modified hydroxyethyl (meth) acrylate, polyethylene glycol mono (Meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3-butoxypropyl (meth) acrylate, and the like.

  The ratio of the blocked tertiary isocyanate group-containing radical polymerizable monomer to the total radical polymerizable monomer is not particularly limited as long as it is a range having two or more blocked tertiary isocyanate groups in one molecule of the acrylic resin (A). However, the range of 10 to 80% by weight, preferably 30 to 70% by weight, based on the total radical polymerizable monomer is suitable.

  The synthesis of the acrylic resin (A) can be performed by a known method, and can usually be performed using a radical polymerization initiator at a temperature of 70 to 160 ° C. The molecular weight of the acrylic resin (A) can be adjusted by the reaction temperature, the amount of initiator, and the like. The reaction concentration is 20 to 80% by weight as an acrylic resin. In particular, in order to increase the polymerization rate, it is preferable to use a peroxide-based or carbonate-based initiator and the reaction temperature is in the range of 80 to 140 ° C. The concentration of the polymerization initiator can be used in the range of 0.01 to 15% by weight of the total radical polymerizable monomer, but is preferably in the range of 0.1 to 10% by weight.

  The weight average molecular weight of the acrylic resin (A) (measured by gel permeation chromatography and determined in terms of polystyrene. The same applies hereinafter for the weight average molecular weight) is the viewpoint of coating film hardness, scratch resistance, weather resistance, finish, etc. In the range of 1,000 to 100,000, preferably 2,000 to 20,000. The acid value of the acrylic resin (A) is 3 to 100 mgKOH / g, preferably 20 to 70 mgKOH / g, from the viewpoint of storage stability and water resistance of the paint, and the hydroxyl value is 0 to 250 mgKOH / g from the viewpoint of curability. g, preferably in the range of 0 to 150 mg KOH / g.

The acrylic resin (A) in (b) can also be synthesized using emulsion polymerization.
Emulsion polymerization can be carried out by a conventional method by a known method. Usually, a mixture of the radical polymerizable monomer and the emulsifier is used at a temperature of 70 to 95 ° C. in the presence of the emulsifier and water, using a polymerization initiator. It can be obtained by carrying out emulsion polymerization (hereinafter, the acrylic resin (A) synthesized by emulsion polymerization is referred to as “aqueous acrylic resin (A-2)”).

  The molecular weight of the aqueous acrylic resin (A-2) can be adjusted by the reaction temperature, the initiator amount, and the like. The reaction concentration is in the range of 1 to 70% by weight as an acrylic resin. The reaction temperature is preferably 70 to 95 ° C. The concentration of the polymerization initiator is preferably in the range of 0.1 to 1.0% by weight of the total radical polymerizable monomer. The amount of the emulsifier is preferably in the range of 0.5 to 5% by weight based on the total radical polymerizable monomer.

  When preparing a mixture of the above-mentioned radical polymerizable monomer and emulsifier, if necessary, mixing and stirring with a high-pressure emulsifier, an ultrasonic emulsifier, a high-pressure colloid mill, a high-pressure homogenizer, etc. so that the desired particle size can be obtained. Preparations can be made using those with high capacity.

  As the emulsifier, for example, sodium salts or ammonium salts such as sulfate ester groups, sulfonic acid groups, and phosphoric acid groups, and commonly used reactive emulsifiers having these can be used.

  Examples of the polymerization initiator include potassium persulfate, sodium persulfate, ammonium persulfate, 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis [2-methyl-N- (2-hydroxy Examples thereof include organic azo compounds such as ethyl) propionamide] and organic peroxides such as benzoyl peroxide and di-t-butyl hydroperoxide. Moreover, it is also possible to use a redox initiator together with these.

  The aqueous acrylic resin (A-2) has a weight average molecular weight of 10,000 to 800,000, preferably 50,000 to 500,000. The aqueous acrylic resin (A-2) may be either a crosslinked type or an uncrosslinked type, and may have a core / shell structure that is generally well known. The acid value of the water-based acrylic resin (A-2) is 3 to 100 mgKOH / g, preferably 5 to 70 mgKOH / g from the viewpoints of storage stability and water resistance of the paint, and the hydroxyl value is 0 from the viewpoint of curability and the like. A range of ˜250 mg KOH / g, preferably 0 to 150 mg KOH / g is suitable.

  The method for obtaining the aqueous product of the acrylic resin (A) is not particularly limited, but, in addition to the aqueous acrylic resin (A-2), for example, the carboxyl group of the acrylic resin (A) is neutralized with a basic compound. It can also be obtained by a method of dispersing in water (hereinafter, the acrylic resin (A) is neutralized with a basic compound and dispersed in water is referred to as “aqueous acrylic resin (A-1)”).

  The aqueous acrylic resin (A-1) is desired, for example, by adding and mixing the basic compound while stirring the acrylic resin (A) obtained as described above, and then adding deionized water while stirring. It can obtain by making it the density | concentration of.

  Examples of the basic compound include ammonia; primary amines such as ethylamine, propylamine, butylamine, benzylamine, monoethanolamine, neopentanolamine, 2-aminopropanol, and 3-aminopropanol; diethylamine, diethanolamine, and diamine. Secondary monoamines such as n- or diisopropanolamine, N-methylethanolamine, N-ethylethanolamine; Tertiary monoamines such as dimethylethanolamine, trimethylamine, triethylamine, triisopropylamine, methyldiethanolamine, dimethylaminoethanol ; Polyamines such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, etc. Rukoto can.

  The basic compound amount is 0.2 mol equivalent to 1.2 mol equivalent, preferably 0.3 mol equivalent to 1 mol equivalent, with respect to 1 mol amount of the carboxyl group in the acrylic resin (A). It is preferable to add.

  As an acrylic resin (A) in this invention, especially following formula (1) or (2)

(In the formula, R ₁ and R ₂ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms). More preferable from the viewpoint.

  Specifically, for example, m-isopropenyl-α, α′-dimethylbenzyl isocyanate is used as the radically polymerizable monomer containing a tertiary isocyanate group in (i) or (b) above, Examples of the nitrogen atom-containing heterocyclic compound include acrylic resins produced using 3,5-dimethylpyrazole or 1,2,4-triazole.

Hydroxyl-containing resin (B)
Component (B) has at least one hydroxyl group selected from acrylic resins, polyester resins and urethane-modified polyester resins having a hydroxyl value of 10 to 250 mgKOH / g and a weight average molecular weight of 1,000 to 200,000. Containing resin. Hereinafter, these resins will be described in detail.

Acrylic resin The acrylic resin suitably used as the component (B) in the present invention can be synthesized by copolymerizing a radical polymerizable monomer according to a conventional method according to a conventional method.

  A conventionally well-known thing can be used as a radically polymerizable monomer, For example, a hydroxyl-containing radically polymerizable monomer, a carboxyl group-containing radically polymerizable monomer, and another radically polymerizable monomer can be used.

  Here, the hydroxyl group-containing radical polymerizable monomer is an essential component. As the hydroxyl group-containing radical polymerizable monomer, the carboxyl group-containing radical polymerizable monomer, and other radical polymerizable monomers, the same ones as mentioned in the acrylic resin (A) can be used in the same manner.

  The weight average molecular weight of the acrylic resin that can be used as the component (B) is in the range of 1,000 to 200,000, preferably 2,000 to 100,000. The hydroxyl value of the acrylic resin is 10 to 250 mgKOH / g, preferably 30 to 150 mgKOH / g.

Polyester resin The polyester resin suitably used in the present invention can be synthesized by an esterification reaction of a polybasic acid and a polyhydric alcohol according to a conventional method according to a known method.

  A polybasic acid is a compound having two or more carboxyl groups in one molecule. For example, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid Examples thereof include acid, het acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid, and anhydrides thereof.

  The polyhydric alcohol is a compound having two or more hydroxyl groups in one molecule, such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-diethyl-1,3-propanediol, diethylene glycol, dipropylene glycol, triethylene glycol, neopentyl glycol, 1,9-nonanediol, 1,4 -Cyclohexanedimethanol, hydroxypivalic acid neopentyl glycol ester, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethylpentanediol, hydrogen Diols such as bisphenol A and trimethylolpropane, Trimethylol ethane, mention may be made of glycerin, trivalent or higher polyols such as pentaerythritol and the like.

  In addition, as the polyester resin, sesame oil fatty acid, coconut oil fatty acid, safflower oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, eno oil fatty acid, hemp oil fatty acid, toll oil fatty acid, dehydrated castor oil fatty acid, etc. (half) A fatty acid-modified polyester resin modified with a dry oil fatty acid or the like can also be used. It is generally suitable that the modified amount of these fatty acids is 30% by weight or less in terms of oil length. Further, a product obtained by partially reacting a monobasic acid such as benzoic acid may be used. In addition, for example, after the esterification reaction of the polybasic acid and the polyhydric alcohol to introduce an acid group into the polyester resin, the polybasic acid such as trimellitic acid or trimellitic anhydride and the anhydride thereof are further reacted. It may be a

  The weight average molecular weight of the polyester resin is suitably in the range of 1,000 to 200,000, preferably 2,000 to 100,000, from the viewpoints of coating film hardness, scratch resistance, weather resistance, finish and the like. The hydroxyl value of the polyester resin is suitably in the range of 10 to 250 mgKOH / g, preferably 30 to 150 mgKOH / g, from the viewpoints of coating film hardness and finish.

Urethane-modified polyester resin Examples of the urethane-modified polyester resin suitably used in the present invention include a resin obtained by urethanizing a polyisocyanate compound to a part of hydroxyl groups in a hydroxyl group-containing polyester resin. .
As the hydroxyl group-containing polyester resin, for example, the above-described polyester resin can be used.

  Examples of the polyisocyanate compound to be reacted with the hydroxyl group-containing polyester resin include aliphatic diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4 (or Cycloaliphatic diisocyanates such as 2,6) -diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,3- (isocyanatomethyl) cyclohexane; tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, etc. Aromatic diisocyanates; organic polymers such as polyisocyanates having a valence of 3 or more such as lysine triisocyanate Cyanate itself, or an adduct of each of these organic polyisocyanates with a polyhydric alcohol, a low molecular weight polyester resin or water, or a cyclized polymer of each organic diisocyanate as described above (for example, isocyanurate), biuret type Examples include adducts. These may be used alone or in combination of two or more.

  The reaction rate of the hydroxyl group-containing polyester resin and the polyisocyanate compound is not particularly limited as long as the hydroxyl value of the urethane-modified polyester resin obtained by the reaction is 10 to 250 mgKOH / g.

  The weight average molecular weight of the urethane-modified polyester resin is 1,000 to 200,000, preferably 2,000 to 100,000. The hydroxyl value of the urethane-modified polyester resin is suitably in the range of 10 to 250 mgKOH / g, preferably 30 to 150 mgKOH / g, from the viewpoints of coating film hardness and finish.

  A method for obtaining an aqueous product of the hydroxyl group-containing resin (B) is not particularly limited. For example, the hydroxyl group-containing resin (B) contains an acid group such as a carboxyl group, and the acid group is a basic compound. It can be obtained by neutralizing and dispersing in water.

  In this case, the acid value of the hydroxyl group-containing resin (B) is in the range of 10 to 100 mgKOH / g, preferably 20 to 70 mgKOH / g. As the basic compound, the same compounds as those mentioned for the aqueous acrylic resin (A-1) can be used.

  The hydroxyl group-containing resin (B) is a basic compound amount corresponding to 0.2 mol equivalent to 1.2 mol equivalent, preferably 0.3 mol equivalent to 1 mol equivalent, with respect to 1 mol amount of the acid group in the hydroxyl group containing resin (B). Neutralizing with is preferable.

  The solid content weight ratio of the blocked tertiary isocyanate group-containing acrylic resin (A) and the hydroxyl group-containing resin (B) blocked with the nitrogen atom-containing heterocyclic compound of the coating composition of the present invention is not particularly limited. Usually, it is suitable that the solid content weight ratio of the component (A) / the component (B) is in the range of 5/95 to 70/30, preferably 10/90 to 40/60.

Catalyst (C)
The component (C) of the aqueous coating composition of the present invention is a curing catalyst that promotes the reaction between the component (A) and the component (B), and is at least one selected from an organometallic system, an acid system and a base system Seed catalyst.
Examples of organometallic catalysts include tetraisopropyl titanate, tetrabutyl titanate, bismuth octylate, lithium acetate, acetylacetone iron (III), zinc 2-ethylhexanoate, copper acetate, vanadium trichloride, tin octylate, dibutyltin Diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dimaleate, tetrabutyltin, dibutyltin oxide, tetra-n-butyl-1,3-diacetyloxydistanoxane, tetra-n-propyl-1,3-diacetyloxy Examples thereof include metal catalysts such as distanoxane and tetra-n-butyl-1,3-dilauryloxydistanoxane, and particularly organic compounds such as tin octylate, dibutyltin diacetate, dibutyltin dilaurate, and distanoxanes. Tin-based compounds are preferred Ku, further, when the low-temperature baking is required, dibutyltin diacetate is preferably used.

  Examples of the acid catalyst include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, butylphosphoric acid, octylphosphoric acid, and the like. Japanese products are also preferably used.

  Examples of the base catalyst include trimethylamine, triethylamine, dimethylcyclohexylamine, N-tetramethylhexane-1,6-diamine, N-pentamethyldiethylenetriamine, 2-methyl-1,4-diazabicyclo [2,2,2]. ] Compounds such as octane can be mentioned.

  These compounds described above as the curing catalyst can be used alone or as a mixture of two or more. The amount of the catalyst varies depending on the type, but is usually about 0.05 to 5 parts by weight with respect to 100 parts by weight of the total solids of the component (A) and the component (B).

  The coating composition of the present invention is particularly suitably used as a coating for automobiles and is particularly useful as a coating for plastic materials. In this case, a polyolefin and / or a chlorinated polyolefin resin is used for imparting adhesion to a plastic material. It is preferable to contain it.

  The polyolefin and the chlorinated polyolefin resin are obtained by chlorinating polyolefins (including modified products obtained by modifying these with (anhydrous) unsaturated carboxylic acid or the like) or the polyolefins.

  Examples of the polyolefins include homopolymers or copolymers of olefins selected from ethylene, propylene, butene, 3-methyl-1-butene, 3-methyl-1-heptene, and the like, and olefins and acetic acid. Examples thereof include copolymers with vinyl, butadiene, acrylic acid esters, methacrylic acid esters, and the like.

  As modified products of these polyolefins, modified products obtained by adding (anhydrous) unsaturated carboxylic acid to the above polyolefins can be suitably used. Examples of the (anhydrous) unsaturated carboxylic acid include (anhydrous) maleic acid, fumaric acid, (anhydrous) itaconic acid, (meth) acrylic acid and the like. The modified product is usually obtained by reacting polyolefins with (anhydrous) unsaturated carboxylic acid in the presence of an organic peroxide or the like.

  Chlorination of the polyolefin or a modified product thereof is usually carried out in a chlorinated solvent such as carbon tetrachloride so that the chlorination rate is 50% or less, preferably 10 to 45%, more preferably 20 to 40%. It can be obtained by heating and dissolving a polyolefin or a modified product thereof and blowing chlorine gas at a temperature of 50 to 120 ° C. for reaction.

  The weight average molecular weight of the polyolefin or a modified product thereof or a chlorinated product thereof is usually about 2,000 to 300,000, particularly preferably about 5,000 to 100,000.

  As the chlorinated polyolefin resin, chlorinated polyethylene, chlorinated polypropylene, chlorinated ethylene-propylene copolymer, chlorinated ethylene-vinyl acetate copolymer and the like are suitable.

  In addition, the chlorinated polyolefin resin includes a chlorinated polyolefin obtained by graft polymerization of a polymerizable monomer. These polymerizable monomers include alkyl esters of (meth) acrylic acid, alkoxyalkyls of (meth) acrylic acid, glycidyl (meth) acrylate, adducts of glycidyl (meth) acrylate and monocarboxylic acid, hydroxyalkyl (meth) Examples include acrylate, acrylic acid, methacrylic acid, maleic acid, and fumaric acid.

  The amount of these polymerizable monomers used is preferably 90 to 10% by weight, particularly 80 to 30% by weight, based on the total amount of the polymerizable monomer and the chlorinated polyolefin. In addition, the chlorinated polyolefin may have a functional group such as a hydroxyl group or a carboxyl group in the molecule.

  In the case of adding polyolefin and / or chlorinated polyolefin, the amount added is in the range of 10 to 200 parts by weight, preferably 20 to 100 parts by weight, based on 100 parts by weight of the total solids of component (A) and component (B). This is suitable from the viewpoints of adhesion to plastic materials and paint stability.

  Here, for example, by introducing maleic anhydride into the chlorinated polyolefin, the maleated chlorinated polyolefin can be synthesized and the adhesion to the plastic material can be improved.

  In addition, the water-based coating composition of the present invention may contain a urethane emulsion that is usually used for the purpose of improving water resistance. Examples of the urethane emulsion include urethane by reacting at least one diol selected from aliphatic and / or alicyclic diisocyanate, polyether diol, polyester diol, and polycarbonate diol, a low molecular weight polyhydroxy compound, dimethanol alkanoic acid, and the like. A prepolymer is prepared, neutralized with a tertiary amine, emulsified and dispersed in water, and then mixed with an aqueous medium containing a chain extender such as polyamine, a crosslinking agent and / or a terminating agent as necessary. Thus, a reaction product obtained until the isocyanate group is substantially eliminated can be used. By the above method, a self-emulsifying urethane emulsion having an average particle size of about 0.001 to 3 μm can be usually obtained.

  As a compounding quantity of a urethane emulsion, it is suitable for it to exist in the range of 0-70 weight part with respect to a solid content total of 100 weight part of (A) component and (B) component, Preferably it is 10-50 weight part. .

  The coating composition of the present invention may further contain a block polyisocyanate compound in which an isocyanate group is blocked with an amino resin and / or an active methylene group-containing compound as a curing agent component.

  The addition amount of the amino resin is suitably in the range of 0 to 30 parts by weight, preferably 5 to 20 parts by weight with respect to 100 parts by weight of the total solid content of the components (A) and (B).

  Examples of amino resins include known partial or fully methylolated amino resins obtained by reacting amino components such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, dicyandiamide and the aldehyde. Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. In addition, a methylolated amino resin etherified with an appropriate alcohol can be used. Examples of alcohols used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl. Alcohol, 2-ethylbutanol, 2-ethylhexanol, etc. can be mentioned.

  The block polyisocyanate compound in which an isocyanate group is blocked with an active methylene group-containing compound can be used mainly for the purpose of improving coating film performance such as low-temperature curability.

  Examples of the active methylene group-containing compound include active methylene compounds such as acetoacetic acid ester and malonic acid diester.

  Among the active methylene group-containing compounds, examples of the acetoacetate include methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, n-propyl acetoacetate, benzyl acetoacetate, phenyl acetoacetate, and malonic acid. Examples of the diester include diethyl malonate, diethyl malonate, diisopropyl malonate, di-n-propyl malonate, diethyl methyl malonate, benzylmethyl malonate, dibenzyl malonate, diphenyl malonate and the like. Moreover, as blocking agents other than these two types of blocking agents, for example, blocking agents such as alcohol-based, oxime-based, amine-based, amide-based, imidazole-based, pyridine-based, and ε-caprolactam-based are used for the total amount of isocyanate groups of polyisocyanate. On the other hand, you may use together in the ratio of 0.3 equivalent or less.

  Examples of the polyisocyanate include aliphatic and / or alicyclic diisocyanates. Suitable aliphatic diisocyanates are those having 4 to 30 carbon atoms, and preferred alicyclic diisocyanates are those having 8 to 30 carbon atoms.

  Specific examples of the diisocyanate compound include 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4 (or 2,4,4) -trimethyl. Examples include -1,6-hexamethylene diisocyanate, lysine diisocyanate, and isophorone diisocyanate.

  The amount of the blocked polyisocyanate compound in which the isocyanate group is blocked with an active methylene group-containing compound is 0 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the total solids of the component (A) and the component (B). It is suitable to be within the range of the part.

  If necessary, the coating composition of the present invention may be added to those usually used for coatings such as UV absorbers, light stabilizers, pigments, surface conditioners, deterioration inhibitors, etc. It can be used as a paint, and other polyols, reactive diluents and other cross-linking agents (for example, epoxy-based, acid-based, alkoxysilane-based cross-linking agents, block polyisocyanates, non-block polyisocyanates, etc. Compound etc.) can also be blended.

  As the ultraviolet absorber, conventionally known ones can be used, and examples thereof include benzotriazole-based absorbers, triazine-based absorbers, salicylic acid derivative-based absorbers, and benzophenone-based absorbers.

  The content of the ultraviolet absorber in the coating composition is usually 0 to 10 parts by weight, particularly 0.2 to 5 parts by weight, more particularly 0.3 to 2 parts by weight, based on 100 parts by weight of the total resin solids weight. It is preferable from the viewpoint of weather resistance and yellowing resistance to be within the range of parts.

  A conventionally well-known thing can be used as a light stabilizer, For example, a hindered amine light stabilizer can be mention | raise | lifted.

  The content of the light stabilizer in the coating composition is usually from 0 to 10 parts by weight, particularly from 0.2 to 5 parts by weight, more particularly from 0.3 to 2 parts by weight, based on 100 parts by weight of the total resin solid content. It is preferable from the viewpoint of weather resistance to be within the range of the part.

  Examples of the pigment include titanium oxide, zinc white, iron oxide, titanium yellow, carbon black, cadmium red, molybdenum red, chromium yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, Colored pigments such as selenium pigments and perylene pigments; extender pigments such as talc, clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, silica, alumina white; mica powder coated with aluminum powder, mica powder, titanium oxide And luster pigments.

  The blending amount of the pigment is generally in the range of 0 to 250 parts by weight, particularly 3 to 150 parts by weight per 100 parts by weight of the total solid content of the component (A) and the component (B).

Next, the coating film forming method of the present invention will be described.
The article to which the coating composition of the present invention is applied is not particularly limited, and examples thereof include the bodies of various vehicles such as automobiles, motorcycles, and containers; molding of household appliances, steel furniture, kitchen appliances, shutters, and the like. Bodies, and cold-rolled steel sheets, galvanized steel sheets, zinc alloy-plated steel sheets, stainless steel sheets, tin-plated steel sheets, etc., metal substrates such as aluminum plates and aluminum alloy plates; various plastics Materials can be raised.

  Moreover, as a to-be-coated object, surface treatments, such as a phosphate process, a chromate process, a complex oxide process, may be given to the metal surface of the said molded object or a metal base material. Furthermore, as the object to be coated, an undercoat film and / or an intermediate coat film such as various electrodeposition paints may be formed on the molded body, metal base material, or the like.

  Although it does not specifically limit as a coating method of this invention coating composition, For example, a wet coating film can be formed with coating methods, such as air spray coating, airless spray coating, rotary atomization coating, and curtain coat coating. In these coating methods, electrostatic application may be performed as necessary. Among these, air spray coating is particularly preferable. Usually, the coating amount of the coating composition is preferably set to an amount of about 10 to 50 μm as the cured film thickness.

  In the case of air spray coating, airless spray coating, and rotary atomization coating, the viscosity of the coating composition is adjusted to a viscosity range suitable for the coating, usually Ford Cup #No. In a 4-viscosity meter, it is preferable to adjust appropriately using an organic solvent and / or water so that the viscosity is within a range of about 15 to 60 seconds at 20 ° C.

  The wet coating film is cured by applying a coating composition to an object to be coated and then heating.

  Heating can be performed by a known heating means. For example, a drying furnace such as a hot air furnace, an electric furnace, or an infrared induction heating furnace can be applied. The heating temperature is suitably in the range of 60 to 140 ° C, preferably 80 to 120 ° C. The heating time is not particularly limited, but a range of 10 to 40 minutes is preferable.

  The coating composition of the present invention can be suitably used particularly for any of primer coatings, intermediate coatings, colored top coatings, colored top base coatings or clear coatings for automobile coatings. It can be more suitably used as a top coat base coat or top coat clear coat.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to the following examples. Hereinafter, “part” and “%” are both based on weight, and the film thickness of the coating film is based on the cured coating film.
(Example)
Resin synthesis (Production Example 1)
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 40 parts of methoxypropyl acetate, heated and maintained at 130 ° C., 40 parts of m-isopropenyl-α, α′-dimethylbenzyl isocyanate, 10 parts of styrene. Part, n-butyl acrylate 34 parts, 2-ethylhexyl acrylate 10 parts, acrylic acid 6 parts and tert-butyl peroxyisopropyl carbonate 5 parts were added dropwise over 3 hours. Next, a mixed solution of 10 parts of methoxypropyl acetate and 1 part of tert-butyl peroxyisopropyl carbonate was added dropwise over 1 hour, followed by aging for 5 hours. Next, 19.2 parts of 3,5-dimethylpyrazole was added to this solution and allowed to react for 4 hours. Acrylic resin 1 having a weight average molecular weight of about 10,000 and an acid value of 40 mg KOH / g (weight concentration of solid content: 70%) )
(Production Example 2)
In a reactor equipped with a stirrer, a reflux condenser, and a thermometer, 40 parts of methoxypropyl acetate was placed and heated to 130 ° C., and 28 parts of Karenz MOI (manufactured by Showa Denko KK, primary isocyanate group-containing monomer), A mixture of 10 parts of styrene, 46 parts of n-butyl acrylate, 10 parts of 2-ethylhexyl acrylate, 6 parts of acrylic acid and 5 parts of tert-butyl peroxyisopropyl carbonate was added dropwise over 3 hours. Next, a mixed solution of 10 parts of methoxypropyl acetate and 1 part of tert-butyl peroxyisopropyl carbonate was added dropwise over 1 hour, followed by aging for 5 hours. Next, 19.2 parts of 3,5-dimethylpyrazole was added to this solution and reacted for 4 hours to give an acrylic resin 2 having a weight average molecular weight of about 10,000 and an acid value of 40 mgKOH / g (weight concentration of 70% solids). )
(Production Example 3)
A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 40 parts of methoxypropyl acetate, heated and maintained at 130 ° C., 40 parts of m-isopropenyl-α, α′-dimethylbenzyl isocyanate, 10 parts of styrene. Part, n-butyl acrylate 34 parts, 2-ethylhexyl acrylate 10 parts, acrylic acid 6 parts and tert-butyl peroxyisopropyl carbonate 5 parts were added dropwise over 3 hours. Next, a mixed solution of 10 parts of methoxypropyl acetate and 1 part of tert-butyl peroxyisopropyl carbonate was added dropwise over 1 hour, followed by aging for 5 hours. Next, 17.4 parts of MEK oxime was added to this solution and reacted for 4 hours to obtain acrylic resin 3 (solid content weight concentration 70%) having a weight average molecular weight of about 10,000 and an acid value of 40 mgKOH / g. It was.
(Production Example 4)
In a reactor equipped with a stirrer, a reflux condenser, and a thermometer, 40 parts of methoxypropyl acetate is placed and heated to 130 ° C., and 20 parts of styrene, 14 parts of n-butyl acrylate, 30 parts of i-butyl methacrylate. A mixture of 30 parts of 4-hydroxybutyl acrylate, 6 parts of acrylic acid and 6 parts of azobisisobutyronitrile was added dropwise over 3 hours. After the dropwise addition, the mixture was aged for 1 hour, a mixed solution of 1 part of azobisdimethylvaleronitrile and 10 parts of methoxypropyl acetate was added dropwise over 1 hour, and further aged for 1 hour. The weight average molecular weight was about 5,000, the acid value was An acrylic resin 4 (solid content weight concentration 66%) having a hydroxyl value of 117 mgKOH / g at 47 mgKOH / g was obtained.
(Production Example 5)
In a reactor equipped with a stirrer, reflux condenser, water separator and thermometer, 105 parts of neopentyl glycol, 273 parts of trimethylolpropane, 320 parts of butylethylpropanediol, 277 parts of adipic acid and 385 parts of isophthalic acid are reacted. After putting in a container and reacting at 220 ° C. for 6 hours, 76 parts of trimellitic anhydride was added and reacted at 170 ° C. for 30 minutes. The weight average molecular weight was about 5,000, the acid value was 35 mgKOH / g, and the hydroxyl value was Thus, a hydroxyl group-containing polyester resin 5 having 140 mgKOH / g was obtained.
(Production Example 6)
300 parts of a hydroxyl group-containing polyester resin 5 is placed in a reactor equipped with a stirrer, a reflux condenser and a thermometer, and 9 parts of hexamethylene diisocyanate is added dropwise at 80 ° C. over 1 hour, followed by reaction for 3 hours. A hydroxyl group-containing urethane-modified polyester resin 6 having a molecular weight of about 7,000, an acid value of 34 mgKOH / g, and a hydroxyl value of 120 mgKOH / g was obtained.
Production of water dispersion (Production Example 7)
While stirring the acrylic resin 1 in an amount of 100 g as a solid content weight, 0.5 g of SCAT24 (manufactured by Sankyo Co., Ltd., tin-based catalyst) and 7.4 g of dimethylethanolamine are added, and deionized water is further nonvolatile. The mixture was added with stirring until the content became 30% to obtain an aqueous dispersion 7.
(Production Example 8)
In a reactor equipped with a stirrer, a reflux condenser and a thermometer, 100 parts by weight of m-isopropenyl-α, α′-dimethylbenzyl isocyanate and 48 parts by weight of 3,4-dimethylpyrazole, 0.15 weight of dibutylhydroxytoluene A monomer 1 was obtained by stirring and heating at 100 ° C. until the isocyanate group completely disappeared.
A mixture of 40 parts of monomer 1, 10 parts of styrene, 37 parts of n-butyl acrylate, 10 parts of isostearyl acrylate, 3 parts of acrylic acid, 2.5 parts of New Coal 707SF (manufactured by Nippon Emulsifier Co., Ltd.) and 100 parts of deionized water Was put into a reactor equipped with a reflux condenser and a thermometer, and stirred at 82 ° C. with 80 parts of deionized water and 0 potassium persulfate. .5 parts of the mixture was added dropwise over 30 minutes. After aging for 2.5 hours, a mixture of 30 parts of deionized water and 0.2 part of potassium persulfate was added dropwise over 30 minutes, and further aged for 2 hours to obtain an aqueous dispersion 8 (particle size 180 nm). .
(Production Example 9)
While stirring the acrylic resin 4 in an amount of 100 g as the solid content weight, 7.4 g of dimethylethanolamine was added, and deionized water was further added with stirring until the non-volatile content became 30%, thereby adding an aqueous dispersion 9. Got.
(Production Example 10)
While stirring the polyester resin 5 in an amount of 100 g as a solid content weight, 5.5 g of dimethylethanolamine is added, and deionized water is further added with stirring until the non-volatile content becomes 30%. Got.
(Production Example 11)
MFK-60X (produced by Asahi Kasei Co., Ltd., active methylene group-containing compound block polyisocyanate compound) in an amount of 30 g as a solid weight, acrylic resin 4 and dimethylethanolamine obtained in Production Example 4 in an amount of 70 g as a solid weight While stirring and mixing 5.1 g, deionized water was added with stirring until the non-volatile content was 30% to obtain an aqueous dispersion 11.
Manufacture of water-based paint composition

  The acrylic resin 1 obtained in Production Example 1 in an amount of 30 parts as a solid weight and the compound 4 obtained in Production Example 4 in an amount of 70 parts as a solid weight were mixed, and further 0.5 parts of SCAT24, After adding and mixing 1 part of Tinuvin 400 (manufactured by Ciba Specialty Chemicals Co., Ltd., UV absorber), 1 part of Sanol LS292 (manufactured by Sankyo Co., Ltd., light stabilizer) and 5.1 parts of dimethylethanolamine, Ford was added. Cup #No. 4 was used to obtain water-based coating composition 1 by adding deionized water with stirring so as to have a viscosity of 20 seconds at 20 ° C.

  Polyester resin 5 obtained in Production Example 5 in an amount of 100 parts as a solid content weight and Alpaste 7679NS in an amount of 15 parts as a solid content weight (aluminum flake paste, manufactured by Toyo Aluminum Co., Ltd., particle size of about 12 μm, thickness 0.1 to 0.2 μm) was stirred and mixed, and then the acrylic resin 1 obtained in Production Example 1 in an amount of 20 parts as a solid weight and MFK-60X in an amount of 10 parts as a solid weight were stirred. Further, 5.3 g of triethylamine was added with stirring. After that, Ford Cup #No. No. 4 was used, and deionized water was added with stirring to a viscosity of 40 seconds at 20 ° C. to obtain an aqueous coating composition 2.

  The aqueous dispersion 10 obtained in Production Example 10 in an amount of 60 parts as solid weight, the aqueous dispersion 7 obtained in Production Example 7 in an amount of 30 parts as solid weight, and 10 parts as solid weight. While stirring and mixing 2 parts of Alpaste 7679NS and BYK320 (manufactured by BYK Chemie) in an amount of 10 parts as a solids weight, the aqueous dispersion 11 obtained in Production Example 11 in an amount of 30% solids weight concentration After gradually adding deionized water so as to be, Samprene UX5100A (manufactured by Sanyo Chemical Co., Ltd., urethane emulsion) in an amount of 10 parts as a solid content weight was further added with stirring. After that, Ford Cup #No. 4 was added with stirring to a viscosity of 40 seconds at 20 ° C. to obtain an aqueous coating composition 3.

  The aqueous dispersion 10 obtained in Production Example 10 in an amount of 25 parts as the solid weight, the aqueous dispersion 7 obtained in Production Example 7 in the quantity of 20 parts as the solid weight, and 5 parts as the solid weight. Amount of water dispersion 11 obtained in Production Example 11 and 30% S-4233 in an amount of 30 parts as a solid content weight (manufactured by Nippon Paper Chemicals Co., Ltd., chlorinated polyolefin, chlorination degree 20%, weight average molecular weight 110,000 ), Samprene UX5100A in an amount of 20 parts as a solid content weight and 70 parts of JR-903 (manufactured by Teika Co., Ltd., rutile titanium oxide) were mixed and sufficiently stirred with a disper. After that, Ford Cup #No. No. 4 was used to add deionized water with stirring to a viscosity of 40 seconds at 20 ° C. to obtain an aqueous primer coating composition 4.

The aqueous dispersion 10 obtained in Production Example 10 in an amount of 25 parts as the solid weight, the aqueous dispersion 8 obtained in Production Example 8 in the quantity of 20 parts as the solid weight, and 5 parts as the solid weight. Amount of water dispersion 11 obtained in Production Example 11, 30% S-4233 in an amount of 30 parts as a solid weight, Samprene UX5100A and JR-903 in an amount of 20 parts as a solid weight (manufactured by Teika Co., Ltd.) 70 parts of rutile type titanium oxide) were mixed and sufficiently stirred with a disper. After that, Ford Cup #No. No. 4 was used, and deionized water was added with stirring to a viscosity of 40 seconds at 20 ° C. to obtain an aqueous primer coating composition 5.
(Comparative Example 1)
After stirring and mixing the polyester resin 5 obtained in Production Example 5 in an amount of 100 parts as a solid weight and the Alpaste 7679NS in an amount of 15 parts as a solid weight, production of an amount of 20 parts as a solid weight Acrylic resin 2 obtained in Example 2 and MFK-60X in an amount of 10 parts by weight as a solid content were added with stirring, and 5.3 g of triethylamine was further added with stirring. After that, Ford Cup #No. No. 4 was used to add deionized water with stirring to a viscosity of 40 seconds at 20 ° C. to obtain an aqueous coating composition 6.
(Comparative Example 2)
After stirring and mixing the polyester resin 5 obtained in Production Example 5 in an amount of 100 parts as a solid weight and the Alpaste 7679NS in an amount of 15 parts as a solid weight, production of an amount of 20 parts as a solid weight Acrylic resin 3 obtained in Example 3 and MFK-60X in an amount of 10 parts by weight as a solid content were added with stirring, and 5.3 g of triethylamine was further added with stirring. After that, Ford Cup #No. 4 was added with stirring to a viscosity of 40 seconds at 20 ° C. to obtain an aqueous coating composition 7.

Preparation of Test Plates In Examples 6 to 9, a TSOP substrate (Toyota super olefin polymer resin substrate; 50 mm × 300 mm × 5 mm) degreased with isopropanol was used as an object to be coated.

  In Example 10 and Comparative Examples 3 and 4, an ABS substrate (acrylonitrile-butadiene-styrene terpolymer resin substrate; 50 mm × 300 mm × 5 mm) degreased with isopropanol was used as the object to be coated.

  The aqueous primer coating composition 4 obtained in Example 4 was spray-coated on the object to be coated to a film thickness of 10 μm, left at room temperature for 10 minutes, and then coated with WB # 713T Silver (Kansai Paint). Acrylic resin / melamine resin-based aqueous base coat paint) was spray-coated to a film thickness of 15 μm, allowed to stand for 3 minutes, and then preheated at 80 ° C. for 10 minutes. Thereafter, SFX # 900 (acrylic resin / isocyanate curing agent-based clear paint manufactured by Kansai Paint Co., Ltd.) is spray-coated on the coating film so as to have a film thickness of 30 μm, left for 3 minutes, and baked at 120 ° C. for 30 minutes. And a test plate was obtained by simultaneously curing the three-layer coating film.

  The water-based primer coating composition 5 obtained in Example 5 was spray-coated on the object to be coated so as to have a film thickness of 10 μm, left at room temperature for 10 minutes, and then the water-based material obtained in Example 2 on the coating film. The coating composition 2 was spray-coated to a film thickness of 15 μm, left for 2 minutes, preheated at 80 ° C. for 10 minutes, and then baked at 120 ° C. for 30 minutes to simultaneously cure the two coating films. It was. Thereafter, SFX # 900 was further spray-coated on the coating film so as to have a film thickness of 30 μm, allowed to stand for 3 minutes, and then baked at 100 ° C. for 30 minutes to be cured to obtain a test plate.

  The water-based primer coating composition 4 obtained in Example 4 was spray-coated on the object to be coated so as to have a film thickness of 10 μm, left at room temperature for 10 minutes, and then the water-based material obtained in Example 2 on the coating film. The coating composition 2 was spray-coated to a film thickness of 15 μm, allowed to stand for 2 minutes, and then preheated at 80 ° C. for 10 minutes. Thereafter, the aqueous coating composition 1 obtained in Production Example 1 was further spray-coated on the coating film so as to have a film thickness of 30 μm, left for 3 minutes and then baked at 120 ° C. for 30 minutes to form a three-layer coating. A test plate was obtained by simultaneously curing the membrane.

  The water-based primer coating composition 4 obtained in Example 4 was spray-coated on the object to be coated so as to have a film thickness of 10 μm, left at room temperature for 10 minutes, and then the water-based material obtained in Example 3 was applied on the coating film. The coating composition 3 was spray-coated to a film thickness of 15 μm, left for 2 minutes, preheated at 80 ° C. for 10 minutes, and then baked at 120 ° C. for 30 minutes to simultaneously cure the two coating films. It was. Thereafter, SFX # 900 was further spray-coated on the coating film so as to have a film thickness of 30 μm, allowed to stand for 3 minutes and then baked at 100 ° C. for 30 minutes to be cured to obtain a test plate.

The aqueous coating composition 2 obtained in Example 2 was spray-coated on the object to be coated so as to have a film thickness of 15 μm, allowed to stand for 2 minutes, and then preheated at 80 ° C. for 10 minutes. Thereafter, SFX # 900 was spray-coated on the coating film so as to have a film thickness of 30 μm, and left for 3 minutes, and then baked at 80 ° C. for 30 minutes to simultaneously cure the two coating films. Got.
(Comparative Example 3)
A test plate was obtained in the same manner as in Example 10 except that the aqueous coating composition 2 was changed to the aqueous coating composition 6 obtained in Comparative Example 1 in Example 10.
(Comparative Example 4)
In Example 10, a test plate was obtained in exactly the same manner as in Example 10 except that the aqueous coating composition 2 was changed to the aqueous coating composition 7 obtained in Comparative Example 2.

  The test plates obtained in Examples 6 to 10 and Comparative Examples 3 to 4 were evaluated by performing yellowing, coating film hardness, xylol wiping property and adhesion test. The performance test results are shown in Table 1.

The performance test test and evaluation method in Table 1 are as follows.
Yellowing: Yellowing of the coating film was visually confirmed.
○: Yellowing is not visually recognized, x yellowing is visually observed.
Coating film hardness: Evaluated by pencil hardness. The test was conducted by using a Mitsubishi pencil “uni” for a pencil scratch test, by placing the pencil core at an angle of about 45 degrees on the coating surface and sliding it forward with force. When scratches were found on the coating film three times or more after five tests, the hardness of the coating film was determined by the hardness of the pencil whose previous scratching was less than three times and was evaluated according to the following criteria.
○: HB or more, Δ: 2B to B, ×: 3B or less.
Xylol wiping property: Using a gauze moistened with xylol to such an extent that it does not drip off, the coated surface after rubbed 20 times in a range of about 10 cm length of the coated surface was observed.
○: No blur is recognized, ×: Blur is recognized.
Adhesiveness: Cut the test plate with a cutter knife so that it reaches the material, make 100 grids of 1mm x 1mm size, stick adhesive cellophane tape on the surface, and peel it off rapidly The coated surface was observed and evaluated according to the following criteria.
○: No peeling is observed, Δ: 1 to 20 peelings of the cross-cut coating film are observed, and X: 30 or more peelings of the cross-cut coating film are recognized.

Claims (13)

(A) An average of two or more blocked tertiary isocyanate groups blocked with a nitrogen atom-containing heterocyclic compound are contained in one molecule, the acid value is 3 to 100 mgKOH / g, and the weight average molecular weight is 1,000 to 100. Selected from acrylic resin, polyester resin, and urethane-modified polyester resin having a hydroxyl value of 10 to 250 mgKOH / g and a weight average molecular weight of 1,000 to 200,000. An aqueous paint composition comprising at least one hydroxyl group-containing resin and (C) a curing catalyst as essential components. The blocked tertiary isocyanate group of the acrylic resin (A) is represented by the following formula (1) or (2)

_2. The water-based paint according to claim 1, wherein R ₁ and R ₂ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Composition. The aqueous acrylic resin (A-1) obtained by neutralizing an acid group in the resin with a basic compound and dispersing in water is used as the acrylic resin (A). The aqueous coating composition as described. Particles obtained by emulsion polymerization of a radically polymerizable monomer containing a group represented by the formula (1) or (2), a carboxyl group-containing radically polymerizable monomer, and other radically polymerizable monomers as the acrylic resin (A) The water-based paint composition according to claim 2, wherein a water-based acrylic resin (A-2) having a diameter in the range of 50 to 500 nm is used. The aqueous coating composition according to any one of claims 1 to 4, wherein the acid value of the hydroxyl group-containing resin (B) is 10 to 100 mgKOH / g. Furthermore, the water-based coating composition of any one of Claims 1 thru | or 5 which contains polyolefin and / or chlorinated polyolefin. The water-based paint composition according to any one of claims 1 to 6, further comprising a urethane emulsion. The aqueous coating composition according to any one of claims 1 to 7, further comprising a blocked polyisocyanate compound having an isocyanate group blocked with an amino resin and / or an active methylene group-containing compound. Furthermore, the water-based coating composition of any one of Claims 1 thru | or 8 which contains a ultraviolet absorber and / or a light stabilizer. A multi-layer coating film forming method for sequentially forming a primer layer, a colored topcoat basecoat layer, and a topcoat clearcoat layer on an object to be coated, wherein the coating composition for forming at least one of them is any one of claims 1 to 9. A method for forming a coating film, which is the water-based coating composition according to claim 1. A multi-layer coating film forming method for sequentially forming a colored topcoat basecoat layer and a topcoat clearcoat layer on an object to be coated, wherein the coating composition for forming at least one of them is any one of claims 1 to 9. A method for forming a coating film, which is the water-based coating composition described in 1. The method for forming a coating film according to claim 10 or 11, wherein the article to be coated is a plastic material. A vehicle body formed by forming a coating film by the coating film forming method according to claim 10.